Who am I?

Jack died in a car accident and found himself in a strange waiting room. 

 

He was informed that it was not yet his time to die, and they would return him to Earth.

 

By the time he was sent back, however, his Body had already been cremated. 

 

Consequently, they needed to find him a new Body to inhabit.

 

Fortunately, under the circumstances—depending on how you look at it—a young woman had passed away, and her Body had not yet been discovered. So, they transferred his consciousness into her and reanimated her.

 

Now, he was her.